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8V Tappet Versions?

G

gasser

Just got it firing!
Joined
Feb 20, 2013
Messages
23
Location
Worcester, UK
Does anyone know how many actual versions of the standard tappet component for this engine have been issued? I am aware that the Moto Guzzi club here in the UK, following an owners survey in early 2012, received a statement from Guzzi UK re-assuring all that they had changed their suppliers. This suggests an improved quality tappet. My 2009 Sport had the original 'flawed' tappet in it from manufacture. These were replaced in April 2010 with the completely re-designed 'MK2' version. These have now failed too. I have been supplied with another new set, manufactured December 2012 that are identical in design, but maybe better quality? Are these a 'Mk3', or is this just wishful thinking on my part?
 
Depends. MkIII version has a B0 part number prefix. They are outwardly identical to the MkII version. I believe the change was due to a change of supplier.

Has your engine been thoroughly cleaned and its oil pump inspected? If not you may as well not bother puting in the new bits.

Pete
 
Whatever the answer, go through the forum looking for Pete's guide of how this repair should be done properly to avoid trouble in the future.
It is so much better to make sure your bike will receive the full monty of the repair than just the tappets.

*edit* Duh! Pete himself outrun me! Hey, don't you sleep down under?
 
New Tappet part number is B014603, so does seem I have the latest variant, which is very re-assuring. It did not feel right putting it back together using the exact same bits. Fingers crossed this will now sort the problem. Thanks for tip on checking the oil pump. Seems I caught the damage very early with the left hand cyclinder suddenly making metallic tapping noises. Only one valve clerance was out by 0.001". The tappets themselves had only just started to get nibbled away, so I am hoping there is no other damage to the pump.
 
Hi Gasser,

Please let us know how you get on. I've just got a very low mileage 2011 Griso, and also thought any issues were pre 2010. I've sent off to the UK owners club for a copy of the survey and Piaggios reply. MIne had the tappet clearance checked at just over 400 miles, not sure when to next get them checked as I believe normal 1st service is at 900 miles ? I wil make sure all the servicing is done as I really want to keep this bike.
 
I have now had chance to inspect and compare my new B0 numbered tappet with the damaged Mk2 and thought my observations may be of some value to others. The new one appears to have a much greater degree of hardening/heat treatment. Of course I have no scientific proof of this, but, the tell tale bluey/straw colouration of heat treated metal extends throughout the entire head of the tappet and is visible through to the neck where the head joins the stem. This compares with the damaged one where the same heat colouration only extends very slightly down the rim of the head. It is much shallower. So in my opinion, the Mk3 version appears to be better tempered/hardened. The other noticable difference is the seat of the tappet. The new one has a machined finish to its seat whereas the original appears to have a ground finish. I have no idea what this means, but is another noticable difference. In conclusion I find this re-assuring that the latest tappet is of an improved quality so hopefully will be far more robust and longer lasting.
 
Pleased to say that I have now rebuilt the engine and all appears sweet. Interestingly, the R/H cam and tappets had no wear at all. Failure had occured only on the L/H side. On dropping the sump I found a load of 'mayo' in the bottom. It was then that I noticed that the L/H cam breather pipe had been completely crushed by the tank and air filter housing. I have never had the tank off so perhaps it was a factory assembly fault? I think this crushed breather explains the 'mayo'. But could it also be a factor in the tappet failure due to compromised lubrication on that side perhaps? Is it just a coincidence that the R/H breather was in perfect working order and no tappet failure on that side, yet L/H breather crushed and tappets failed this side?
 
Now that is very interesting.

I've long wondered about how the bikes that fail are being ridden and where.

If people are only doing shortish trips and especially if they do a lot of riding in the wet I can see water in the oil being a major issue. As I've previously stated I can't get one to fail. Thing is that I and most of my customers live in the Southern Tablelands or Greater West of NSW with a few South Coasters thrown in for good measure. Now while it can be wet down the south coast the tablelands and central west are as dry as you can get. Also I don't ride the Griso much in the wet, my Mana offers much better weather protection so if its raining I grab the Mana keys, simple.

When you ride in the rain the water spray from the front wheel has a radical effect on engine oil temperature as it sprays directly onto the sump. I know from checking the temperature of the oil, (I have one of those goofy oil temp dipsticks.) that in the dry regardless of ambient temperature the oil temp hovers about 120*C unless I'm stuck in traffic. That is plenty hot enough to sublime off any. Water from the oil and it'll be expelled through the breather system, (If its working as it should!). Hit some wet though and the oil temperature will instantly drop as low as 60*C depending on the ambient temperature that is way too low for all the wet to be expelled and yes, mayonnaise will be the result.

Now Mayo is a lousy lubricant but it will still *Sort Of* work in a hydrodynamic bearing. Where it will have severe problems is in a sliding interface like the one between a cam and a flat tappet!

It would be interesting to hear what sort of riding people who are experiencing failures are doing, where and when and whether there is a lot of wet weather riding involved?

Pete
 
Maybe thats the cause for some of the failures in the UK, it's seems as if it's always raining here :)
 
I have discussed this with my local dealer who also inspected the crushed breather pipe. He agreed with my assessment as this being probable cause for the mayo, but was not so sure that it would have compromised lubrication sufficiently to cause the tappet failure. I use my bike purely for pleasure, long distance runs during our summer months etc. I do not use it for any short trips or commuting so it always gets properly warmed up. Indeed, last year I toured France, taking in Monaco and the Alps and it performed brilliantly. Usually I stop riding by the end of September each year when autumn starts to bite, but last year was different. I spent a weekend touring Wales in early November in Freezing but dry conditions, ice on the road etc. Bike was fine. But the very next time I started it up (this January) I could hear noises coming from the L/H valve train. Coincidence? I know it must sound like I am aligning the stars for my own convenience, but for me it seems highly probable that due to the crushed breather and extremely cold conditions, mayo formed on the L/H side, compromised the lubrication and pop, tappet/cam expires.
 
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